Cityfight was a passing fad at our store. Perhaps the incessant cut and stab wounds from the Imperial buildings after every game sapped the will to fight. Perhaps the sheer fiddliness of placing models in buildings.
Though if we are to go off the amount of terrain given in the Cityfight Codex as an example of a Cityfight- then we have all been playing Omega Cityfight in normal 40k for years.
It was a little shocking and disheartening to consider that GW seriously believed 1-2 buildings to be a city, as it brought up the question- Do they seriously think normal 40k should be fought on a desert board (i.e. with even less terrain than this)?
I think the Strategems are what make Cityfight different to 40k (considering we use as much terrain in both), all the terrain, LOS, movement, etc of Cityfight is pretty much a clarification of 40k- nothing more.